Conventionally, in the production of semiconductor devices, fine processing by lithography using a photoresist has been performed. The fine processing is a processing method for forming fine convexo-concave shapes corresponding to the following pattern on the surface of a substrate by: forming a thin film of a photoresist on a semiconductor substrate such as a silicon wafer; irradiating the resultant thin film with active rays such as ultraviolet rays through a mask pattern in which a pattern of a semiconductor device is depicted; developing the thin film; and subjecting the substrate to etching processing using the resultant photoresist pattern as a protecting film.
However, recently, high integration of semiconductor devices has progressed and the adopted active rays tend to have a shorter wavelength, such as an ArF excimer laser (193 nm), replacing a KrF excimer laser (248 nm). Following such a tendency, the influence of reflection of active rays on a semiconductor substrate has become a large issue.
As an underlayer film between the semiconductor substrate and the photoresist, the use of a film known as a hardmask containing a metal element such as silicon or titanium has been performed. In this case, the resist and the hardmask have components largely differ from each other, so that the removal rates of the resist and the hardmask by dry etching largely depend on the type of a gas used for dry etching. By appropriately selecting the type of a gas, the hardmask can be removed by dry etching without a large decrease in the film thickness of the photoresist.
As described above, in the production of semiconductor devices in recent years, for achieving various effects such as the reflection preventing effect, a resist underlayer film has become disposed between the semiconductor substrate and the photoresist. The studies of a composition for a resist underlayer film have been performed; however, due to the diversity of characteristics required for the composition and so on, development of a novel material for the resist underlayer film is desired.
For example, a resist underlayer film containing a polysiloxane using a silane having an ester bond is described (see Patent Document 1, Patent Document 2, and Patent Document 3).